For teams tracking the frontier-model race, the signal worth watching is not a public launch but who gets early access. Elon Musk said on June 28, 2026 that xAI's Grok 4.5 has entered private beta at SpaceX and Tesla, its first deployment ahead of a wider release. According to Musk, Grok 4.5 is built on xAI's 1.5 trillion-parameter V9 foundation model, which finished training on May 26, and adds data from the Cursor coding environment in supplemental training. Musk claimed early evaluations put its performance close to, and potentially above, Anthropic's Claude Opus. xAI has not published benchmarks or a system card, so the capability claims remain unverified. The choice to dogfood the model inside Musk's own engineering-heavy companies suggests a focus on technical reasoning and code over consumer chat.
Grok 4.5 Private Beta: 1.5T Params, Cursor Data, xAI’s Machine